The invention relates to a method for determining the position of the cores in an injection mould, comprising the steps essentially consisting of: selecting a core Rrep in a population of cores with the least difference from the mean of the measured differences between k cores and the theoretical three-dimensional spatial model, positioning this core Rrep in space relative to at least one of the functional faces of a theoretical three-dimensional spatial model of the core, and repositioning core support points so that they can support the core Rrep in the position corresponding to its repositioning in space performed in the previous step.